Battery life is one of the chief considerations in mobile device design. Various power saving schemes are used and employed to achieve longer results. Most of them are based on peripheral elements and sensors usage and software controls. For example, for wireless devices, the power to the screen may be turned off when not in use. Also, in the software space, tickling the kernel and using background processing have resulted in power savings.
However, on multi-core devices (which are typically included in modern smartphones and tablets), there is no optimization of the power and frequency on the core level inside the processor. Tasks are scheduled by the operating system scheduler based on core vacancy considerations and the locality of pages in processor caches and memory.
Furthermore, the methods above assume that processor cores are identical. However, impurities in silicon result in variations between cores—different power/current usage, different temperature curve, and accordingly different frequency at which the core can or may run when computing a task. This means that the same computational task, when executed on two seemingly identical cores, may result in a certain percentage (%) more power consumption when executed on one core than if executed on the other core, for example, even though execution of the task took the same number of cycles to complete and was executed at the same core frequency.